PM8000 series meters
*Warning: Installation and maintenance of this device should only be performed by qualified, competent personnel that have appropriate training and experience with high voltage and current devices. Failure to follow the instructions / warnings in the Meter Installation Guide can result in permanent damage to the meter, severe injury or death.
The attached document discusses Red Leg Delta (also called "High Leg Delta") configuration and how it works in WYE Mode and DELTA Mode.
The document can also be downloaded from here